Banks and other financial institutions usually utilize banknote processing devices such as a banknote counting machine, a banknote sorting machine and the like to authenticate, count or sort banknote. In an existing art, the banknote processing device includes a separating part, configured to gradually separate the stacked banknote one by one; an identification part, configured to identify and count the banknote; and an accumulation part, configured to accumulate the banknote counted by the banknote identification part. Furthermore, the banknote processing device also includes a rejection part which is configured to receive the banknote which is identified by the banknote identification part as rejection.
The banknote identification part includes an image sensor which is configured to acquire a banknote image so as to discriminate the authenticity of the banknote. A common image sensor is a charge-coupled image sensor (abbreviated as CCD) and a contact image sensor (abbreviated as CIS), and both the CCD and the CIS acquire the banknote image by illuminating the banknote through the light of a light source. However, since the number of the banknote to be counted and sorted by the financial institution is large, the banknote processing device generally needs to work continuously for several hours. Consequently, after the banknote processing device continuously works for a long time, the heat generated by the continuous work of a motor and other banknote drive devices enables the temperature of the banknote processing device to be increased continuously, so that the luminous intensity of the image sensor will be obviously changed; moreover, certain electrostatic accumulation may be produced when the banknote continuously pass through a transport passage, and the continuous electrostatic accumulation will also cause the working instability of the image sensor, resulting in a decline of the quality of an image generated by the image sensor and further influencing the banknote identification accuracy.
In the existing art, in order to avoid the problem that the banknote identification rate is obviously declined due to the long-time continuous work of the banknote processing device, the working personnel usually turns off a power supply of the banknote processing device manually after the banknote processing device works for a preset period of time, and enables the banknote processing device to be powered on again after the banknote processing device is powered off for a set period of time. This method not only requires the timing operation of the working personnel, but also requires the banknote processing device to be paused, thereby having the problem of low working efficiency.
An effective solution is not proposed yet for the problem in the existing art that the processing efficiency is relatively low when the banknote identification rate is obviously decreased due to the long-time continuous work of the banknote processing device.